1. Field of the Invention:
The present invention relates to a feed additive composition. More specifically, it relates to a feed additive composition for ruminant animals wherein a biologically active substance is coated with a coating composition which is stable in the animal's rumen but which allows the release of the biologically active substance in the abomasum and subsequent digestive tract, thus making possible the digestion of the biologically active substance without significant loss due to rumen microbe degradation.
2. Description of the Related Art
When biologically active substances such as amino acids, vitamins, etc. are orally administered to ruminants like cattle and sheep, the majority of the active substance is decomposed by microorganisms which are present in the rumen, and the substance is not utilized effectively by the animal. Accordingly, biologically active substances which are capable of passing through the rumen without decomposition and which are then effectively digested and absorbed in the abomasum and subsequent digestive tract are desired in the field of ruminant feeds, nutrient preparations, medicines, etc.
Feed additives for ruminants containing biologically active substances have been proposed in the past. These materials are coated with fatty acids with 12 or more carbon atoms, hardened animal or vegetable fats and oils, etc. Unfortunately, however, these particles coated with fats and oils are stable not only in the rumen, but also in the abomasum and subsequent digestive tract, making release and digestion of the biologically active substances poor. For this reason, methods of adding to the protective substances substances which enhance release in the abomasum and subsequent digestive tract have been proposed. In these methods, the biologically active materials are dispersed in coating materials and granulated, or are coated with the coating materials.
A method for the dispersion of a biologically active substance in a protective substance has been proposed in, for example, Japanese Unexamined Patent Application 168351/85A , wherein granules are produced containing a biologically active substance, 20% by weight or more of calcium carbonate, 10% by weight or more of an aliphatic monocarboxylic acid of 14 or more carbon atoms, a hardened fat or oil, etc. Also, In Japanese Examined Patent Application 10780/84B a method is proposed for dispersing 30-50% by weight of a biologically active substance into a protective substance comprising 10-35% by weight of salt of aliphatic monocarboxylic acid of 14-22 carbon atoms or ricinoleic acid, the remainder comprising an aliphatic monocarboxylic acid of 14-22 carbon atoms, ricinoleic acid, hardened fats and oils, or the like.
A method for coating a biologically active substance with a protective substance has also been proposed in Japanese Unexamined Patent Application 317053/88A, wherein a biologically active substance is coated with a protective substance which comprises an aliphatic monocarboxylic acid of 12-24 carbon atoms, a hardened fat and oil, lecithin, and a glycerin fatty acid ester.
However, in these methods for preparing dispersions of biologically active substances in protective substances, since the biologically active substance is present near the particle surface, it is necessary to significantly lower the content of the biologically active substance for its protection, and, considering that, in the case of water-soluble biologically active substances, since the residence time in the rumen is from a few dozen hours to a few days, sufficient protection thereof is difficult to provide. In addition, when coating is accomplished using a protective coating consisting of lecithin, a glycerin fatty acid ester, and a fat and an oil, the strength of the coating layer in the rumen is insufficient and the problem of poor protection remains. Furthermore, the lecithin and glycerin fatty acid esters are expected to have an emulsifying effect on the fat and oil, but considering the time of passage through the abomasum and subsequent digestive tract, the degree of release is insufficient.
Finally, a method has been proposed for providing a coating using a synthetic polymer which is insoluble in the environment of the rumen, but which is soluble in the strongly acidic abomasum, in order to make use of the difference in pH of the rumen and the abomasum. However, considering the fact that this method uses an organic solvent during coating it leads to high costs, as well as to other negative factors, and thus cannot be said to be a fully adequate method.